Certain navigation devices and mobile phones conventionally exist which perform the function of navigating routes for automobiles and pedestrians based on position information obtainable from the Global Positioning System (GPS).
For example, Japanese Laid-Open Patent Publication No. 2002-357444 refers to a navigation system based on sound and the display of routing maps in a mobile terminal such as a mobile phone.
According to this navigation system, information regarding the user's present position and desired destination is transmitted from the mobile terminal to a server, and then map data including the present position and the desired destination is downloaded from the server and thereafter transmitted to and stored in the mobile terminal, which outputs the stored map data as sounds and images. The mobile terminal automatically emits a sound to notify the user of output by means of a speaker and displays the output in the form of images on the display screen of the mobile terminal.
In this case, it is not necessary for the mobile terminal to perform the function of updating map data, and it is possible to have the benefits of such navigation at low cost and with minimal power consumption.
However, according to the navigation system described in Japanese Laid-Open Patent Publication No. 2002-357444, the user must be in a traveling mode or otherwise move while viewing the map image shown on the display screen of the mobile terminal, making it unnecessarily inconvenient for the user.
Moreover if the guidance information provided is in the form of sounds, it may not be clearly received, considering the limitations to the volume and quality of sound produced by the speaker of the mobile terminal, and at times, sound guidance may not be easily recognized if the mobile terminal is carried by the user in his clothing pocket.
On the other hand, Japanese Laid-Open Patent Publication No. H11-160087 refers to a pedestrian navigation device which must be equipped with an IC card for storing map information and thus operates on a stand alone basis. In the navigation device of such invention, the user inputs a starting point and a desired destination, whereupon the device searches a route from the starting point to the destination, reads map information, and the searched route and the user's position are measured by present position measuring means and then displayed on a map, which includes certain indicators such as left and right turns by means of certain types of vibration patterns generated by vibration generating means.
However, the pedestrian navigation device described in the above-mentioned Japanese Laid-Open Patent Publication No. H11-160087 is rather inconvenient to use, because the user must provide for an IC card in advance for storing map information regarding certain areas of destination for which he requires or desires guidance, to enable him to utilize the navigation device at the desired destination.
Further, in the case of Japanese Laid-Open Patent Publication No. H11-183183, the navigation system intended for installation in an automobile comprises a navigation device which displays a map provided through map information generating means, simultaneously generating a sound signal from sound guide generating means to provide route guidance information, while detecting the generation of the sound signal to output a control signal, and a vibration device which is independent of the navigation device, where the navigation device vibrates according to the control signal output as a result of the detection of the sound signal generated. The driver of the automobile puts the vibration device in his clothing pocket or the like to alert him to the outputted sound guidance and map being displayed by the navigation device when the vibration device vibrates.
However, while the afore-mentioned navigation system which separately consists of the navigation device and the vibration device is suitable for a car navigation system, the same would not be convenient for a pedestrian to use because he will have to carry both devices and view the map being displayed on the screen while walking.
Another type of navigation system which has been introduced in Japanese Laid-Open Patent Publication No. 2001-204062 is configured in such manner that wireless communication base stations which respectively have a communication area and a center station are provided, whereby the center station retains map information, carries out route searching, and provides a portable terminal for communicating navigation information to a wireless base station. This navigation system is intended to eliminate the inconvenience posed by portable terminal retaining map data in a portable navigation system utilizing the GPS system.
According to the configuration of this navigation system, the portable terminal is provided with a vibration generating unit and/or a sound generating unit for receiving vibration data and/or sound guidance data in addition to map information and route guidance information from the center station, and provides guidance by means of vibration and/or sounds. As guidance means, the length and the number of vibrations generated vary according to the contents of the guidance information, such as a left turn or right turn, for example.
However, according to the navigation system described in Japanese Laid-Open Patent Publication No. 2001-204062, Dedicated Short Range Communications (DSRC) base stations are provided as wireless base stations, and the position of the portable terminal can be identified only within the area covered by the DSRC base station with which the portable terminal is communicating in particular, making the provision for precise route guidance difficult if not impossible. In addition, the navigation system suffers from the limitation that it cannot be combined with other navigation systems capable of carrying out unrestricted route searches.
Moreover, according to this navigation system, while the user is walking, the DSRC portable terminal successively transmits information on the user's position back to the center station, and the center station delivers route data to the user by causing the DSRC portable terminal to vibrate as a means of notification. As a method of route instruction, the DSRC portable terminal vibrates for such length of time and for such number of times to signify a turn to be made at a corner, going up or down the stairs, or in combination with a traffic signal, but the route instructions are provided only upon arrival at a certain location. Accordingly, guidance information cannot be provided in advance, for example, information on the distance required to be traversed (e.g., 70 m) before a guide point, such as an intersection.
In the case of a pedestrian navigation device constituted in a mobile phone with a GPS receiver, navigation information in the form of maps and route guidance information is accessed from an information delivery server. A user generally carries the mobile phone in his pocket or the like while walking, and takes out the mobile phone to view a display screen or to make or receive a phone call if necessary. The user carries out a similar operation to obtain navigation guidance information through the facility of the display screen of the mobile phone. This is not exactly convenient, because the user should preferably travel along a guided route, and walk while checking a map, a route, a present position, and the like shown on the display screen of his mobile phone at specified guide points or locations such as an intersection accompanying a left or right turn, or the neighborhood of the intended destination. In addition to the guiding method by which visual images are shown on the display screen, however, it would be preferable if the mobile phone is also capable of providing guidance even through non-visual means, and equipped with notifying means other than that normally employed for alerting the user that guidance information is about to be relayed or otherwise available visually.